Vessel sealing instrument with reduced thermal spread and method of manufacture therefor

ABSTRACT

An electrosurgical vessel sealing instrument having a first and a second opposing jaw member at a distal end thereof, wherein each jaw member includes a jaw housing, a seal plate having a tissue contacting surface and a side wall, and an insulating region disposed on the side wall of the seal plate. The instrument includes the ability to move the jaw members relative to one another from a first position wherein the jaw members are disposed in spaced relation relative to one another to a second position wherein the jaw members cooperate to grasp tissue. The insulating region enables precision overmolding of the jaw housing to the seal plate, while advantageously reducing thermal spread and edge cutting during vessel sealing procedures.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of U.S. patentapplication Ser. No. 14/887,555, filed on Oct. 20, 2015, which is acontinuation application of U.S. patent application Ser. No. 14/546,106,filed on Nov. 18, 2014, now U.S. Pat. No. 9,161,806, which is adivisional application of U.S. patent application Ser. No. 13/404,435filed on Feb. 24, 2012, now U.S. Pat. No. 8,887,373, the entire contentsof each of which are incorporated herein by reference.

BACKGROUND

1. Technical Field

The present disclosure relates to electrosurgical instruments andmethods for performing surgical procedures and, more particularly, to anelectrosurgical vessel sealing instrument with a jaw assembly having oneor more insulating members associated with the sealing plate thatprovide reduced thermal spread and reduced edge cutting while enablingimproved dimensional tolerances during the prototyping and manufacturingprocess.

2. Background of Related Art

A hemostat or forceps is a simple pliers-like tool that uses mechanicalaction between its jaws to constrict tissue and is commonly used in opensurgical procedures to grasp, dissect and/or clamp tissue.Electrosurgical forceps utilize both mechanical clamping action andelectrical energy to effect hemostasis by heating the tissue and bloodvessels to coagulate, cauterize and/or seal vascular tissue.

Using electrosurgical forceps, a surgeon can elect to seal, cauterize,coagulate, or desiccate tissue, or simply reduce or slow bleeding bycontrolling the intensity, frequency and duration of the electrosurgicalenergy applied to the tissue. Generally, the electrical configuration ofelectrosurgical forceps can be categorized in two classifications: 1)monopolar electrosurgical forceps; and 2) bipolar electrosurgicalforceps.

Monopolar forceps utilize one active electrode associated with theclamping end effector and a remote patient return electrode or pad thatis attached externally to the patient, e.g., on the leg or buttocks.When electrosurgical energy is applied, the energy travels from theactive electrode, to the surgical site, through the patient, and to thereturn electrode.

Bipolar electrosurgical forceps utilize two generally opposingelectrodes that are generally disposed on the inner facing or opposingsurfaces of the end effectors (e.g., jaws of the instrument) which are,in turn, electrically coupled to an electrosurgical generator. Eachelectrode is charged to a different electric potential. Since tissue isa conductor of electrical energy, when the end effectors are utilized toclamp or grasp tissue therebetween, the electrical energy can beselectively transferred through the tissue to cause a change therein andeffect sealing of the vessel.

Certain surgical procedures require sealing blood vessels or vasculartissue. The term “vessel sealing” is defined as the process ofliquefying the collagen in the tissue so that the tissue cross-links andreforms into a fused mass. In order to form a burst-resistant and soundvessel seal, the application of sealing energy should be targeted to thespecific region of tissue to be sealed. Excessive thermal energy shouldnot be allowed to spread to adjacent areas of tissue, as this maydiminish the integrity of a resulting seal since the energy required toform the seal is dissipated into the surrounding tissue rather than intothe region intended to be sealed. For the purposes herein the term“thermal spread” refers generally to the heat transfer (heat conduction,heat convection or electrical current dissipation) dissipating along theperiphery of the electrically conductive or electrically active surfacesof an electrosurgical instrument to adjacent tissue. This can also betermed “collateral damage” to adjacent tissue. One form of collateraldamage is referred to as “edge cutting” whereby current concentrationsnear the edge of the electrode partially or completely sever the vesselbeing sealed. The reduction and control of such thermal spread andattendant collateral damage is therefore a desirable objective in thedesign of a vessel sealing instrument.

SUMMARY

The present disclosure relates to an electrosurgical vessel sealinginstrument having a seal plate disposed on the opposing faces of thevessel-sealing jaws. It has been found that reducing the height of theseal plate side walls may minimize thermal spread, yet, too much of areduction in sidewall height may result in excessive currentconcentrations resulting in increased edge cutting. Therefore, sealplate height must be precisely controlled in order to achieve optimumperformance, e.g., minimal thermal spread with minimal edge cutting. Thevertical dimension of the seal plate is determined at least in part bythe manufacturing process used to form the jaw member. Using prior artovermolding techniques, it is difficult to maintain the tolerancesnecessary to form a jaw member having the desired minimal thermal spreadand minimal edge cutting properties since variations in edge height wereunavoidable. During product development cycles, where numerous anddifferent prototypes may be built, the overmolding process may not becost-effective and may yield unsatisfactory results, particularly when aprototype jaw member needs to be fabricated precisely for evaluationpurposes.

In some embodiments, a seal place in accordance with the presentdisclosure includes an obverse tissue-contacting sealing surface, areverse surface, and a surrounding side wall defining an edgetherebetween. The side walls of the seal plate incorporate one or moreinsulators that precisely define the shutoff depth, e.g., a linedescribing a delineation on the side wall between the conductive andnon-conductive portions of the seal plate. An insulator may be disposedwithin a recess or groove formed along a side wall of the seal plate. Aninsulator may be continuously disposed along a side wall of the sealplate or may be discontinuously disposed, e.g., in a notched, dentil, orother suitable pattern. An insulator according to the present disclosuremay be flush with a surface of the seal plate, or alternatively mayprotrude from the surface of the seal plate, may be recessed into thesurface of the seal plate, or may be disposed upon the surface of theseal plate. The groove, notches, or other recesses disposed within theseal plate may be formed by photolithography.

In an embodiment, a reverse surface of the seal plate includes aplurality of ribs and/or valleys defined thereupon. An insulating layerhaving an obverse side and a reverse side is intimately and conformallyfixed to the seal plate mounting surface such that the valleys and/orribs of the seal plate reverse surface engage corresponding features ofthe insulator obverse face. An edge of the seal plate defined by thesealing surface and the side wall is radiused. The ribbed pattern of theseal plate and insulator, and the radiused edge of the seal plateprovides optimal current paths while minimizing thermal spread andcollateral damage, e.g., edge cutting. In some embodiments a base plateis fixed to a reverse face of the insulator to facilitate mounting ofthe seal plate/insulator to a jaw housing. A reverse face of the baseplate may include notched, grooved, or dovetailed features adapted toenhance adhesion between the base plate and the jaw housing.

By the disclosed arrangement, sealing current is uniformly concentratedwithin the sealing surface of the jaws (e.g., the seal plate) whileconcurrently providing enhanced electrical and thermal isolation alongthe side walls of the seal plate. The disclosed arrangement of theelectrode insulating material and the electrically conductive sealingsurface provides a more consistent, high quality seal and effectivelyreduces thermal spread to adjacent tissue during use. Preferably, thegeometry of the insulating substrate and seal plate also isolates thetwo electrically opposing electrodes formed by opposing seal plateswithin a pair of jaws from one another, thereby reducing the possibilitythat tissue or tissue fluids can create an unintended bridge or path forcurrent travel.

In an embodiment, the disclosed electrosurgical instrument includes afirst jaw member and a second opposing jaw member at a distal endthereof. Each jaw member includes a jaw housing, a tissue contactingseal plate, and an insulating layer disposed therebetween attaching theseal plate to the jaw housing. The seal plate includes one or more ribsextending from a reverse surface of the seal plate into the insulatinglayer. At least one of the jaw members is movable from a first positionwherein the jaw members are disposed in spaced relation relative to oneanother to a second position wherein the jaw members cooperate to graspvessel tissue therebetween.

Also disclosed is an electrosurgical vessel sealing system. In anembodiment, the disclosed vessel sealing system includes a source ofelectrosurgical vessel sealing energy adapted to operably couple to anelectrosurgical vessel sealing instrument. The electrosurgicalinstrument includes a first jaw member and a second opposing jaw memberat a distal end thereof. Each jaw member includes a jaw housing, atissue contacting seal plate, and an insulating layer disposedtherebetween attaching the seal plate to the jaw housing. The seal plateincludes one or more ribs extending from a reverse surface of the sealplate into the insulating layer. At least one of the jaw members ismovable from a first position wherein the jaw members are disposed inspaced relation relative to one another to a second position wherein thejaw members cooperate to grasp vessel tissue therebetween.

Also disclosed is an electrosurgical instrument that includes a firstjaw member and a second opposing jaw member at a distal end of theelectrosurgical instrument. Each jaw member comprises a seal platehaving a top tissue contacting surface, and a side wall extending from aperipheral edge of the tissue contacting surface wherein the side wallincludes an outer surface and a bottom edge. An insulator is disposed onan outer surface of the side wall. A jaw is housing fixed to the bottomedge of the side wall and at least a portion of the insulating region.The jaw housing may be formed by any suitable manner of manufacture, forexample without limitation, overmolding. At least one of the jaw membersis movable from a first position where the jaw members are disposed inspaced relation relative to one another to a second position where thejaw members cooperate to grasp tissue therebetween.

The present disclosure is also directed to a method of manufacturing ajaw member. The disclosed method includes the steps of providing a blankseal plate, applying a resist mask to a reverse surface of the sealplate defining a plurality of valley regions, etching the masked reversesurface of the seal plate to form a plurality of valleys thereindefining at least one rib on the reverse surface of the seal plate,removing the resist mask from the seal plate, affixing an insulatinglayer to the reverse surface of the seal plate, and affixing a reversesurface of the insulating layer to a jaw housing.

Yet another method of manufacturing a jaw member in accordance with thepresent disclosure includes the steps of forming a raw seal plate havinga tissue contacting surface and a side wall. A photoresist material isapplied to at least a portion of the raw seal plate to form a coating. Aportion of the coating corresponding to an insulating region is exposedto an energy source, e.g., a photolithographic energy source such aswithout limitation ultraviolet light or electron beam energy. Thecoating is developed to reveal a region of the side wall correspondingto the insulating region. An insulating material is applied to theregion of the side wall corresponding to the insulating region. Theremaining coating is removed from the raw seal plate, and a jaw housingis overmolded to a bottom side of the raw seal plate and at least a partof the insulating region. A recessed region may be formed in the sidewall corresponding to the insulating region.

Yet another electrosurgical vessel sealing system is disclosed hereinthat includes a source of electrosurgical vessel sealing energy and anelectrosurgical instrument configured to operably couple to the sourceof electrosurgical energy. The electrosurgical instrument includes afirst jaw member and a second opposing jaw member at a distal end of theelectrosurgical instrument. Each jaw member comprises a seal platehaving a top tissue contacting surface, and a side wall extending from aperipheral edge of the tissue contacting surface wherein the side wallincludes an outer surface and a bottom edge. An insulator is disposed onan outer surface of the side wall. A jaw is housing fixed to the bottomedge of the side wall and at least a portion of the insulating region.The jaw housing may be formed by any suitable manner of manufacture, forexample without limitation, overmolding. At least one of the jaw membersis movable from a first position where the jaw members are disposed inspaced relation relative to one another to a second position where thejaw members cooperate to grasp tissue therebetween.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the subject instrument are described herein withreference to the drawings wherein:

FIG. 1 is a functional view of an example embodiment of a vessel sealingsystem utilizing a hemostat-style vessel sealing instrument inaccordance with the present disclosure;

FIG. 2 is a functional view of another example embodiment of a vesselsealing system utilizing a vessel sealing instrument suitable forminimally-invasive procedures in accordance with the present disclosure;

FIG. 3 is a cross-sectional view of a prior art jaw member;

FIG. 4 is a cross-sectional view of an example embodiment of a jawmember that includes a flush-mounted insulating shutoff incorporated inthe side wall of the seal plate in accordance with the presentdisclosure;

FIG. 5 is a cross-sectional view of another example embodiment of a jawmember that includes a surface-mounted insulating shutoff disposed onthe side wall of the seal plate in accordance with the presentdisclosure;

FIG. 6 is a perspective view of yet another example embodiment of a sealplate having a ribbed structure on a reverse surface thereof inaccordance with the present disclosure;

FIG. 7 is a perspective view of the FIG. 6 embodiment wherein a jawhousing is overmolded thereupon to form a jaw member in accordance withthe present disclosure;

FIG. 8 is a side, cutaway view of the FIG. 6 embodiment of a vesselsealing jaw member in accordance with the present disclosure;

FIG. 9 is a perspective view of still another embodiment in accordancewith the present disclosure wherein a jaw housing is overmoldedthereupon to form a jaw member;

FIG. 10 illustrates an example step of a method of manufacturing a jawmember in accordance with the present disclosure wherein a seal plateblank is provided;

FIG. 11 illustrates an example step of a method of manufacturing a jawmember in accordance with the present disclosure wherein a resist maskis applied to a seal plate blank;

FIG. 12 illustrates an example step of a method of manufacturing a jawmember in accordance with the present disclosure wherein an etchant isapplied to a seal plate blank;

FIG. 13 illustrates an example step of a method of manufacturing a jawmember in accordance with the present disclosure wherein a resist maskis removed;

FIG. 14 illustrates an example step of a method of manufacturing a jawmember in accordance with the present disclosure wherein an insulatinglayer is applied to a surface of a seal plate;

FIG. 15 illustrates an example step of a method of manufacturing a jawmember in accordance with the present disclosure wherein insulatingmaterial is removed therefrom;

FIG. 16 illustrates an example step of a method of manufacturing a jawmember in accordance with the present disclosure wherein a jaw housingis overmolded to a seal plate;

FIG. 17 illustrates an example seal plate blank adapted for use in amethod of manufacturing a jaw member in accordance with the presentdisclosure;

FIG. 18 illustrates an example step of a method of manufacturing a jawmember in accordance with the present disclosure wherein a seal plateblank is positioned in a forming die;

FIG. 19 illustrates an example step of a method of manufacturing a jawmember in accordance with the present disclosure wherein a forming dieforms a seal plate blank into a seal plate;

FIG. 20 is a perspective view of an example seal plate adapted for usein a method of manufacturing a jaw member in accordance with the presentdisclosure;

FIG. 21 is a cross-sectional view of an example seal plate adapted foruse in a method of manufacturing a jaw member in accordance with thepresent disclosure;

FIG. 22 is a cross-sectional view of an example seal plate having aphotoresist coating and undergoing exposure in accordance with thepresent disclosure;

FIG. 23 is a cross-sectional view of an example seal plate undergoingphotoresist developing in accordance with the present disclosure;

FIG. 24 is a cross-sectional view of an example seal plate undergoingetching in accordance with the present disclosure;

FIG. 25 is a cross-sectional view of an example seal plate undergoinginsulation application in accordance with the present disclosure;

FIG. 26 is a cross-sectional view of an example seal plate undergoingphotoresist removal in accordance with the present disclosure;

FIG. 27 is a cross-sectional view of an example seal plate with a firstovermold in accordance with the present disclosure;

FIG. 28 is a cross-sectional view of an example seal plate with a secondovermold in accordance with the present disclosure;

FIG. 29 is a perspective view of an example seal plate having acontinuous recess in accordance with the present disclosure;

FIG. 30 is a perspective view of the FIG. 29 seal plate havinginsulating material deposited in the etched recess in accordance withthe present disclosure;

FIG. 31 is a perspective view of an example jaw member incorporating theseal plate of FIG. 30 in accordance with the present disclosure;

FIG. 32 is a perspective view of an example seal plate having a seriesof notched recesses in accordance with the present disclosure;

FIG. 33 is a perspective view of the FIG. 32 seal plate havinginsulating material deposited in the notched recesses in accordance withthe present disclosure;

FIG. 34 is a perspective view of an example jaw member incorporating theseal plate of FIG. 33 in accordance with the present disclosure;

FIG. 35 is a cross-sectional view of another example seal plate having aphotoresist coating and undergoing exposure in accordance with thepresent disclosure;

FIG. 36 is a cross-sectional view of another example seal plateundergoing photoresist developing in accordance with the presentdisclosure;

FIG. 37 is a cross-sectional view of another example seal plateundergoing insulation application in accordance with the presentdisclosure;

FIG. 38 is a cross-sectional view of another example seal plateundergoing photoresist removal in accordance with the presentdisclosure;

FIG. 39 is a cross-sectional view of another example seal plate with afirst overmold in accordance with the present disclosure;

FIG. 40 is a cross-sectional view of another example seal plate with asecond overmold in accordance with the present disclosure;

FIG. 41 is a perspective view of another example seal plate having acontinuous surface-mounted insulator in accordance with the presentdisclosure;

FIG. 42 is a perspective view of another example jaw memberincorporating the seal plate of FIG. 41 in accordance with the presentdisclosure;

FIG. 43 is a perspective view of another example seal plate having aplurality of insulators of varying width in accordance with the presentdisclosure;

FIG. 44 is a perspective view of yet another example seal plate having aplurality of insulators in a staggered arrangement in accordance withthe present disclosure;

FIG. 45 is a perspective view of still another example seal plate havinga plurality of insulators in a diagonal arrangement in accordance withthe present disclosure;

FIG. 46 is a perspective view of an additional example of a seal platehaving a plurality of insulators of varying width in accordance with thepresent disclosure;

FIG. 47 is a perspective view of yet another additional example of aseal plate having a plurality of insulators having a sawtooth pattern inaccordance with the present disclosure;

FIG. 48 is a perspective view of still another additional example of aseal plate having a plurality of insulators of varying height inaccordance with the present disclosure; and

FIG. 49 illustrates current flows within an example embodiment of a jawmember in accordance with the present disclosure.

DETAILED DESCRIPTION

Particular embodiments of the present disclosure are describedhereinbelow with reference to the accompanying drawings; however, thedisclosed embodiments are merely examples of the disclosure, which maybe embodied in various forms. Well-known functions or constructions arenot described in detail to avoid obscuring the present disclosure inunnecessary detail. Therefore, specific structural and functionaldetails disclosed herein are not to be interpreted as limiting, butmerely as a basis for the claims and as a representative basis forteaching one skilled in the art to variously employ the presentdisclosure in virtually any appropriately detailed structure.

In the drawings and in the descriptions that follow, the term“proximal,” as is traditional, shall refer to the end of the instrumentthat is closer to the user, while the term “distal” shall refer to theend that is farther from the user. The term “obverse” shall refer to adirection facing towards a tissue contacting surface of a jaw member,while “reverse” shall refer to the direction facing away from a tissuecontacting surface of a jaw member. In addition, as used herein, termsreferencing orientation, e.g., “top”, “bottom”, “up”, “down”, “left”,“right”, “clockwise”, “counterclockwise”, “upper”, “lower”, and thelike, are used for illustrative purposes with reference to the figuresand features shown therein. It is to be understood that embodiments inaccordance with the present disclosure may be practiced in anyorientation without limitation. In this description, as well as in thedrawings, like-referenced numbers represent elements which may performthe same, similar, or equivalent functions.

Referring to FIG. 1, an embodiment of a vessel sealing system 10 inaccordance with the present disclosure is shown generally and includes abipolar forceps 100 having an end effector assembly 130 that includesfirst and second jaw members 110 and 120 that mutually cooperate tograsp, seal, and/or divide a tubular vessel “T”. As shown, handlemembers 115 and 116 of instrument 100 are of the scissors type;-*however, any suitable type of handle is envisioned within the scope ofthe present disclosure. The handle members 115 and 116 offer a surgeon agripping position from which to grasp forceps 100 and to transmit aclamping pressure to end effector assembly 130. During use, handlemembers 115 and 116 are moved closer to one another to cause jaw members110 and 120 to apply a clamping force and electrosurgical energy to thetubular vessel T to effect a tissue seal. Once sealed, the tubularvessel T can be cut along the seal to separate the vessel T leaving twoscored ends.

Forceps 100 further includes an electrical cable 22 extending therefromthat couples forceps 100 to a source of electrosurgical energy 20, e.g.,a generator 20. In some embodiments, a source of electrosurgical energy,and/or a power source, such as without limitation, a rechargeablebattery (not shown), may be included within forceps 100. Cable 22 maycouple to generator 20 via connector 21, and is adapted to providevessel sealing energy to jaw members 110 and 120.

In another example embodiment depicted in FIG. 2, a vessel sealingsystem 10′ includes an endoscopic forceps 200 having a housing 225including a shaft 212 extending therefrom that enables a surgeon toperform minimally-invasive (e.g., endoscopic or laparoscopic) surgicalprocedures. Shaft 212 may alternatively have a shorter, or longer,length than that shown in FIG. 2, which may be desirably utilized invarious endoscopic and/or open surgical procedures. Rotating assembly218 is attached to a distal end of housing 225 and is rotatable ineither direction about a longitudinal axis “A-A” defined through theshaft 212. In some embodiments, rotating assembly 218 is rotatableapproximately 180 degrees in either direction about the longitudinalaxis “A-A”. Rotation of rotating assembly 218 correspondingly rotatesend effector assembly 230 about the longitudinal axis “A-A” tofacilitate manipulation of tissue. In some embodiments, shaft 212 isbifurcated at a distal end 214 thereof to form ends 214 a and 214 b,which are configured to receive end effector assembly 230.

Housing 225 is formed from two housing halves that engage one anothervia a series of mechanical interfaces to form an internal cavity forhousing the internal working components of instrument 10′. For thepurposes herein, the housing halves are generally symmetrical and,unless otherwise noted, a component described with respect to a first ofthe housing halves will have a similar component which forms a part of asecond of the housing halves.

Handle assembly 223 includes a first handle 226 and a second handle 224.End effector assembly 230 is attached to distal end 214 of shaft 212 andincludes a pair of opposing jaw members 210 and 220. Second handle 224is selectively movable about a pivot (not explicitly shown) from a firstposition in spaced relation relative to first handle 226 to a secondposition in closer proximity relative to first handle 226, which, inturn, imparts movement of jaw members 210 and 220 relative to oneanother, e.g., from an open to closed position about tissue T. Forillustrative purposes, jaw member 210 may be referred to as an upper jawmember 210 and jaw member 220 may be referred to as a lower jaw member220. First and second handles 226, 224 are ultimately connected to adrive assembly (not explicitly shown) which, together, mechanicallycooperate to impart movement of jaw members 210, 220 from an openposition wherein the jaw members 210, 220 are disposed in spacedrelation relative to one another, to a clamping or closed positionwherein, e.g., jaw members 210, 220 cooperate to grasp tissue Ttherebetween and to deliver electrosurgical energy to tissue T.

Forceps 200 further includes an electrical cable 229 extending fromhousing 225 which couples instrument 200 to a source of electrosurgicalenergy, e.g., a generator 228. Cable 229 may couple to generator 228 viaconnector 227, and is adapted to provide vessel sealing energy to jawmembers 210 and 220.

Jaw members 210, 220 may be electrically isolated from one another suchthat electrosurgical energy can be effectively transferred through thetissue disposed therebetween to form the seal.

End effectors 130 and/or 230 may additionally or alternatively be curvedin order to reach specific anatomical structures. For example,dimensioning end effectors 130 and/or 230 at an angle of about 50° toabout 70° is preferred for accessing and sealing specific anatomicalstructures, e.g., those anatomical structures relevant toprostatectomies and cystectomies, such as without limitation the dorsalvein complex and the lateral pedicles.

FIG. 3 illustrates a cross-sectional view of prior art jaw member 250.Prior art jaw member 250 includes a seal plate 251 having atissue-contacting surface 252 and sides walls 253. The side walls 253are embedded in a jaw housing 254 that can be formed by overmolding. Theshutoff height, i.e., the height of the exposed conducive surface of theside wall 253 is denoted by H1 a on the left and H1 b on the right. Asdemonstrated in FIG. 3, flashing 255 and 256 from the overmoldingprocess remains disposed upon the side walls 253. As can be appreciated,due to the limitations of the overmolding process, the amount offlashing may vary considerably around the junction of seal plate 251 andjaw member 254. In the example prior art jaw member 250 presented inFIG. 3, flashing 255 extends slightly up the left sidewall 253 over alength denoted by H2 a, while, on the opposite side, flashing 256extends further up the right sidewall 256 over a length denoted by H2 b.These manufacturing variations result in a left side shutoff distance H1a being greater than right side shutoff distance H1 b. During use, thesedifferences in shutoff dimension may contribute to unbalanced or unevensealing and/or may contribute to collateral tissue damage, since themanufactured shutoff dimensions vary from the intended design dimensionand cause uneven or suboptimal delivery of energy to tissue.

While in theory the overmolding process may be modified to reduceflashing in the prior art design, in practice, the requiredmodifications may result in lower production yields, require longermanufacturing times, be more labor-intensive, may require more expensiveprocesses and/or tooling, and generally are not cost effective.

Turning now to FIG. 4, an example embodiment of a jaw member 400 inaccordance with the present disclosure is described in detail. Thedescribed features of jaw member 400 are representative of one or moreof the jaw members as described hereinabove (e.g., jaw members 110 and120 of FIG. 1 and/or jaw members 210 and 220 of FIG. 2), and whenincluded in an end effector assembly having opposing jaws (e.g., endeffector assembly 130 of FIG. 1 and/or end effector assembly 230 of FIG.2) include mutually corresponding component features that cooperate topermit rotation about a pivot pin (not explicitly shown) to effectivelygrasp, seal, and/or divide tissue.

Jaw member 400 includes an electrically conductive electrode or sealplate 412 having a tissue-contacting surface 411 and side walls 423. Asshown, seal plate 412 has a generally inverted U-shaped cross section;however, seal plates in accordance with the present disclosure are notlimited to the inverted U-shape shown herein. Seal plate 412 may beformed by any suitable manner of formation, including withoutlimitation, stamping, casting, machining, and the like. A knife slot 420may be defined in the tissue-contacting surface 411 of seal plate 412.Tissue-contacting surface 411 of seal plate 412 has a perimetric edge417 that includes a radius 415. In some embodiments, radius 415 has aradius of about 0.05″. One or more stop members 422 are disposed upon asurface 411 and are configured to limit the minimum clearance betweenjaw members during use to within a specified range, typically about0.001″ to about 0.006″. Each stop member 422 is made from an insulativematerial.

As seen in FIGS. 4, 9, and 29-31, a groove 419 is defined along an outerside wall 423 of seal plate 412. In the FIG. 4 embodiment, groove 419runs longitudinally around side wall 423 and extends downward to abottom surface 431 of side wall 423. An insulator 414 is disposed withingroove 419. Insulator 414 may be formed form any suitablehigh-temperature, biocompatible material, including without limitationpolyimide. An inner support 435 is included within seal plate 412 thatis adapted to provide additional strength and rigidity to the jaw member400. In some embodiments, inner support 435 may be formed frompolyphthalamide (PPA) thermoplastic polymer, such as Amodel®manufactured by Solvay Advanced Polymers of Alpharetta, Ga., UnitedStates. Inner support 435 may be formed by any suitable method ofmanufacture, including without limitation, overmolding.

Jaw member 400 includes a jaw housing 428 that is fixed to a reverse end432 of side walls 423 and/or inner support 435. Jaw housing 428 supportsthe combination of seal plate 412 and inner support 435. In someembodiments, jaw housing 428 may be formed from non-conductive material,such as without limitation, high-strength ceramic material, and may beformed by overmolding. Jaw housing 428 may include a number of featuresdesigned to facilitate the mounting thereof on an instrument, e.g., ahinge plate 424 extending from a proximal end thereof. (See FIG. 31.)The hinge plate 424 may include additional features adapted to pivot,mount, and articulate jaw member 400, including without limitation,pivot hole 425 and/or cam slot 426. A conductor (not explicitly shown)operably couples seal plate 412 to a source of vessel sealing energy,e.g., generators 20, 228.

The configuration of jaw member 400 enables the shutoff height H1 a, H1b to be consistently defined despite variations in tolerance, e.g.,flashing, which is a byproduct of the overmolding process. As can beseen in FIG. 4, the left side of jaw housing 428 includes a flashingregion 455 having a height H3 a, while the right side of jaw housingexhibits flashing 456 that extends further upward (denoted as H3 b) thandoes flashing 455. Advantageously, the shutoff height H1 a and H1 b ofdisclosed jaw member 400 is determined by the top edge 419 of insulator414, not by the imprecise top edges 455, 456 of jaw housing 428. Thus, aconsistent shutoff height is achieved by a jaw member 400 in accordancewith the present disclosure despite dimensional variances that mayresult from overmolding, or other suitable manufacturing processes.

Turning now to FIGS. 32-34, another embodiment of a jaw member 460according to the present disclosure is illustrated wherein one or morenotches 469 are defined in an outer surface 461 of side wall 463 andhaving an insulator 464 disposed therein to form a series of one or moreinsulating regions 466. A jaw housing 468 is joined to seal plateassembly 462 as described hereinabove. A portion of each insulatingregion 464 extends beyond an overmolded region 469 of jaw housing 468 toform an alternating series of conductive regions 465. It is believedthat the described arrangement of conductive regions 465 may influencecurrent paths within and around seal plate 462 that consequently reducethe incidence of collateral tissue damage, e.g., edge cutting andthermal spread. As shown, the width of an insulating region 464 and aconductive region 465 is about equal, e.g., about 1:1; however, in someembodiments the ratio of insulating region width to conductive regionwidth may range from about 1:5 to about 5:1, and can be in a range ofabout 1:100 to about 100:1. This ratio may vary along the edge(s) of aseal plate, such that, for example and without limitation, the width ofsuccessive insulating regions increases or decreases as viewed acrossthe face of a seal plate side wall.

Turning now to FIGS. 5, 41, and 42, yet another embodiment of a jawmember 500 in accordance with the present disclosure is presentedwherein a seal plate 512 includes an insulating band 514 disposed arounda periphery thereof. Insulating band 514 may be formed from any suitableheat resistant and biocompatible material, such as without limitation,polyimide. Insulating band 514 may be overmolded, formed from heatshrink material, applied using photoresistive mask, and the like. Jawmember 500 includes a seal plate support 535 that may be formed fromPPA, and a jaw housing 535 that may be formed by overmolding, aspreviously discussed. One or more stop members 522 are disposed upon asurface 511 of seal plate 512 and are configured to limit the minimumclearance between jaw members, as discussed above.

FIGS. 43-48 illustrate additional example embodiments of a seal plate inaccordance with the present invention. In particular, several envisionedalternative arrangements of peripheral insulating regions are disclosed.It is believed that by varying the widths of the insulating regionsand/or the conductive regions around the periphery of the seal plate,collateral damage may be managed in a controlled manner. Certainarrangements of insulating regions, for example, may deliver sealingenergy in a manner best suited for certain types of tissue. In someembodiments, the insulation pattern may enable the precise delivery ofedge energy which may, in turn, allow procedures in proximity tosensitive anatomical structures, which would have been ill-advised withprior-art instruments, to be successfully performed.

For example, in FIG. 43 a seal plate having a series of insulatingregions 601 et seq., each having a successively decreasing width isshown. At a proximal end the insulating regions 601 a, 601 b, 601 c etseq. are wider and at a distal end insulators 601 k et seq. arenarrower. In FIG. 44, seal plate 610 includes a series of staggeredinsulating regions 611, 612. FIGS. 45-48 illustrate various alternativeinsulator configurations: diagonal (FIG. 45), increasing/decreasing(FIG. 46), sawtooth or triangular (FIG. 47), and varying height (FIG.48). It is to be understood that these are merely example insulatingregion configurations, and a seal plate in accordance with the presentdisclosure may have variation and combinations of these and otherinsulator configurations.

An example method of manufacturing the various jaw members describedhereinabove is now described with reference to FIGS. 17-28 and FIGS.35-40. A seal plate blank 914, which may be formed by any suitablemanner, e.g., stamping via a blanking die, is provided in FIG. 17. Sealplate blank 914 is placed between forming dies 902, 903 in a die press901, as depicted in FIG. 18. The die press 901 extends driving formingdie 902 downward over blank 914 and forming die 903, which forms a rawseal plate 915 having desired features, e.g., side wall 923 and knifechannel 920, as seen in FIGS. 20 and 21.

In FIG. 22, a raw seal plate 1015 is coated with a photoresist material1040. In the present example, a positive photoresist 1040 is shownwherein exposure to light (typically ultraviolet light) or an electronbeam provided by a photolithographic energy source P renders photoresist1040 soluble to a photoresist developer. In other embodiments, anegative photoresist material may be employed wherein the non-exposedportions of coating 1040 are rendered soluble.

In the present positive photoresist example embodiment, energy source Pexposes an area of photoresist 1040 corresponding to the desiredinsulation pattern, e.g., corresponding to groove 419 as shown in FIG.29, notches 469 seen in FIG. 32, insulating regions 601 a et seq. seenin FIG. 43, insulating regions 611, 612 as shown in FIG. 44, insulatingregions 621 of FIG. 45, insulating regions 631 et seq. as seen in FIG.46, insulating regions 641 of FIG. 47, and/or insulating regions 651shown in FIG. 48.

In FIG. 23, the exposed photoresist 1040 is developed by rinsing thephotoresist coating 1040 with a developer solution 1042, resulting in aregion 1041 of raw seal plate 1015 being revealed. In FIG. 24, anetchant solution 1043 is applied to the exposed portion 1041 of raw sealplate 1015 resulting in a notch 1019 being defined therein. In FIG. 25,the notch 1019 is filled, partially or completely, with an insulatingmaterial, e.g., polyimide. In FIG. 26, a rinsing or stripping solution1044 is applied to the seal plate 1015 and the remaining photoresist1040 is thereby removed.

In the step illustrated in FIG. 27, an inner support 1035 is formedwithin seal plate 1015 by overmolding. In an embodiment, the innersupport 1035 is formed from polyphthalamide thermoplastic polymer, e.g.,Amodel®. In the step shown in FIG. 28, a jaw housing 1028 is overmoldedto the bottom side of the seal plate 1015 and inner support 1035combination formed in the FIG. 27 step, forming a jaw member 1000. Seealso FIGS. 31 and 34. Additionally, stop members 1022 may be fixed to atissue-contacting surface 1012 seal plate 1015 by any suitable process,such as without limitation, overmolding. A conductor 1030 adapted tooperably couple seal plate 1015 to a source of electrosurgical (e.g.,sealing) energy may be fixed to seal plate 1015 by any suitable matterof attachment, including without limitation soldering, crimping,welding, brazing, and/or threaded fastener.

In another example method of manufacturing a jaw member 1100 inaccordance with the present disclosure, in FIG. 35, a raw seal plate1115 is coated with a photoresist material 1140. As in the priorexample, a positive photoresist 1140 is shown. An energy source Pexposes an area of photoresist 1040 corresponding to the desiredinsulation pattern, e.g., corresponding to the surface-mounted insulator514 depicted in FIG. 41. In FIG. 36, the exposed photoresist 1140 isdeveloped by rinsing the photoresist coating 1140 with a developersolution 1142, resulting in a region 1141 of raw seal plate 1115 beingrevealed. In FIG. 37, region 1141 is coated with an insulating material,e.g., polyimide, forming a surface-mounted insulating strip (see, e.g.,FIG. 41). In FIG. 38, a rinsing or stripping solution 1144 is applied tothe seal plate 1115 thereby removing any the remaining photoresist 1140from seal plate 1115, leaving insulator 1114 disposed on side wall 1113as can be readily appreciated.

In the step illustrated in FIG. 39, an inner support 1135 is formedwithin seal plate 1115 by overmolding. In an embodiment, the innersupport 1135 is formed from polyphthalamide thermoplastic polymer. Inthe step shown in FIG. 40 a jaw housing 1128 is overmolded to the bottomside of the seal plate 1115 and inner support 1135 combination formed inthe FIG. 39 step, forming a jaw member 1100. Additionally, stop members1122 may be fixed to a tissue-contacting surface 1112 of seal plate 1115by any suitable process, including without limitation overmolding. Aconductor 1130 adapted to operably couple seal plate 1115 to a source ofelectrosurgical (e.g., sealing) energy may be fixed to seal plate 1115by any suitable matter of attachment, including without limitationsoldering, crimping, welding, brazing, and/or threaded fastener.

Turning now to FIGS. 6, 7, and 8, another example embodiment of a jawmember 300 in accordance with the present disclosure is described indetail. The described features of jaw member 300 is representative ofone or more of the jaw members as described hereinabove (e.g., jawmembers 110 and 120 of FIG. 1 and/or jaw members 210 and 220 of FIG. 2),and when included in an end effector assembly having opposing jaws(e.g., end effector assembly 130 of FIG. 1 and/or end effector assembly230 of FIG. 2) include mutually corresponding component features thatcooperate to permit rotation about a pivot pin (not explicitly shown) toeffectively grasp, seal, and/or divide tissue.

Jaw member 300 includes an electrically conductive electrode or sealplate 312 and an insulating substrate or insulator 314. Insulator 314 isconfigured to securely engage electrode 312. This may be accomplishedby, e.g., stamping, by overmolding, by overmolding a stampedelectrically conductive sealing plate and/or by overmolding a metalinjection molded seal plate. Insulating substrate 314, seal plate 312,and the outer, non-conductive jaw housing 328 (see FIG. 7) areconfigured to limit and/or reduce many of the known undesirablecollateral effects related to tissue sealing, e.g., thermal spread andedge cutting.

Electrode 312 may also include an outer peripheral edge 317 that has aradius 315. In this embodiment insulator 314 meets electrode 312 alongan adjoining edge that is generally tangential to the radius and/ormeets along the radius. At the interface, electrode 312 is raised, e.g.,more obverse, relative to insulator 314.

Seal plate 312 includes one or more ribs 316 extending from a reversesurface or underside 319 thereof. As shown in the example embodiment ofFIGS. 6, 7, and 8, ribs 316 are substantially straight and orientedtransverse to a longitudinal axis “B-B” of the jaw member 300. In otherenvisioned embodiments, ribs 316 may oriented longitudinally or at anyangle with respect to a longitudinal axis “B-B” of the jaw member 300.Ribs 316 may define a path that includes circular, undulating, sawtooth,stepped, crosshatched, zigzag, or other shape path. As shown in theFigures, ribs 316 have a width to spacing (W:S) ratio of about 1:5;however, the W:S ratio may range from 1:100 to about 100:1. A pluralityof ribs 316 may have a similar widths “W” or dissimilar widths “W”. Insome embodiments, the width “W” of successive ribs 316 may increase,decrease, or vary according to a pattern. The spacing “S” of the valleys321 (see FIG. 8) formed between ribs 316 may be similar or dissimilar,and may increase, decrease, or vary according to a pattern. Theeffective depth “D” of seal plate 312 may range from about 0.001″ toabout 0.25″, and in an embodiment may be about 0.013″.

Insulating layer 314 is disposed on a reverse surface 319 of seal plate312. Insulating layer 314 may be formed from any suitabletemperature-resistant material having electrical and/or thermalinsulating properties, including without limitation polyimide. As shownin FIGS. 6, 7, and 8, insulating layer 314 conforms to the ridges 316and/or valleys of seal plate 312. Insulating layer 314 may be formed byany suitable manner of fabrication, including without limitation,overmolding, backfilling, and conformal coating. During use in a vesselsealing procedure, it is believed the combination of ribs 316 andinsulating layer 314 together with radius 315 acts to control currentpaths within seal plate 312, which, in turn, reduces thermal spread andreduced edge cutting while optimizing the delivery of sealing energy tovessel tissue.

A backing plate 327 may be fixed to a reverse surface or underside 311of insulating layer 314. Backing plate 327 may include one or moreadhesion-enhancing features 323 that promote bonding between backingplate 327 and insulation layer 314. As shown, adhesion-enhancingfeatures 323 include an interlocking dovetail arrangement; however anysuitable texturing or surface features may be advantageously employed,including without limitation grooves, ribs, rod-like protrusions, andthe like. Backing plate 327 may be formed from any suitablehigh-temperature metallic or non-metallic material, and in anembodiment, a material having dielectric properties differing from thatof insulating layer 314 may be employed to further control currentconcentrations and thermal spread during vessel sealing procedures.

As mentioned above, jaw member 300 includes a jaw housing 328 thatsupports the combination of seal plate 312 and insulating layer 314,and, optionally, backing plate 327. In some embodiments, jaw housing 328may be formed from non-conductive material, such as without limitation,high-strength ceramic material, and may be formed by overmolding. Jawhousing 328 may include a number of features designed to facilitate themounting thereof on an instrument, e.g., a hinge plate 324 extendingfrom a proximal end thereof. (See FIGS. 7 and 8.) The hinge plate 324may include additional features adapted to pivot, mount, and articulatejaw member 300, including without limitation, pivot hole 325 and/or camslot 326. A conductor (not explicitly shown) operably couples seal plate312 to a source of vessel sealing energy, e.g., generators 20, 228.

A cable or wire 330 is electromechanically joined to seal plate 312 tofacilitate the delivery of electrosurgical energy thereto. Wire 330 maybe joined to seal plate 312 at junction 331 by any suitable manner ofelectromechanical coupling, including without limitation, crimping,soldering, welding, brazing, backstab connector, and the like. As shown,junction 331 is located in proximity to hinge plate 324 to facilitaterouting of wire 330 proximally though the instrument. A proximal end ofwire 330 (not explicitly shown) may be adapted to operably couple with asource of electrosurgical energy.

Ribs 316 may be formed by any suitable manner of manufacture, includingwithout limitation, molding, stamping, machining, water jet cutting, orphotolithography. An example embodiment of a fabrication method inaccordance with the present disclosure is illustrated in FIGS. 10-16. Ablank seal plate 815 having a reverse surface or underside 814 isprovided as shown in FIG. 10. In FIG. 11, a resist mask 830 is appliedto reverse surface 814 of seal plate 815 to expose regions 818. Regions818 are etched to form valleys 821, and, correspondingly, those areas ofreverse surface 814 protected by resist mask 830 form ribs 816.

As shown in FIG. 12, an etchant E is utilized to etch the desired seriesof valleys 821. In the step exemplified in FIG. 13, a rinsing agent R isapplied to remove any remaining etchant and/or to remove resist mask830, exposing the finished seal plate 815 having the desired series ofribs 816 and valleys 821. In the step exemplified in FIG. 14, aninsulating layer 819 is applied to reverse surface 814 of seal plate 815to form a seal plate subassembly 817. In some embodiments, insulatinglayer 819 is formed from polyimide by overmolding. Optionally, as shownin FIG. 15, the upper portion of insulating layer 819 may be etched,machined, or otherwise removed thereby leaving insulation 819′ disposedonly within each valley 821. An electrically conductive wire 830 isjoined to seal plate 815 at junction 831. Wire 830 may be joined to sealplate 815 by any suitable manner of fixation, including withoutlimitation, crimping, soldering, welding, brazing, backstab connector,and the like. In the step exemplified in FIG. 16, a jaw housing 828 isjoined to seal plate subassembly 817 to form a jaw member 800. Jawhousing 828 may be joined to seal plate subassembly 817 by overmolding,by adhesive bonding, by mechanical coupling (e.g., threaded fastener,interlocking clips, or tabs), or by any suitable manner of fixation.

In some embodiments, jaw housing 828 is formed from non-conductivematerial, such as without limitation, high-strength ceramic material, orhigh-strength thermosetting polymeric material. Jaw housing 828 may beformed by e.g., overmolding, powder molding, injection molding,machining, stamping, or casting. Jaw housing 828 may include a number offeatures designed to facilitate the mounting thereof on an instrument,e.g., a hinge plate 824 having defined therein a pivot hole 825 and/or acam slot 826.

Referring now to FIG. 6, in order to achieve the necessary gap range(e.g., about 0.001″ to about 0.006″) between opposing jaw members 110,120 or 210, 220 to properly seal tissue, a jaw member 300 may includeone or more stop members 322 that limit the movement between jaw membersto within the specified range. Each stop member 322 is made from aninsulative material and is dimensioned to limit opposing movement of jawmembers to within the above gap range.

Seal plate 312 may be formed from any suitable temperature-resistant,electrically conductive material, such as without limitation, stainlesssteel. The tissue-contacting surface 318 of seal plate 312 may includean electrically-conductive lubricious coating (not explicitly shown)formed from, e.g., graphite-impregnated polytetrafluoroethylene (PTFE),mica-impregnated PTFE, metal-impregnated ceramic, or titanium nitride.The lubricious coating may reduce the tendency of vessel walls and/orother targeted tissue from undesirably adhering to seal plate 312.

A knife channel 320 may be defined through the center of jaw member 300such that a knife having a distally-facing cutting edge (not explicitlyshown) may cut through tissue T grasped between opposing jaw members,e.g., jaw members 110, 120 and/or jaw members 210, 220 when such jawmembers are in a closed position. Details relating to the knife channel320, trigger 240 (see FIG. 2), knife and a knife actuation assemblyassociated therewith (not shown) are explained in limited detail hereinand explained in more detail with respect to commonly-owned U.S. Pat.Nos. 7,156,846 and 7,150,749 to Dycus et al.

FIG. 49 depicts current flows “C1” and current concentrations “C2”within an embodiment of a jaw member 500 during use in accordance withthe present disclosure. During use in a vessel sealing procedure, thecombination of ribs 516 and insulating layer 514 together with radius515 may act to control current flows C1 to generally within seal plate512. As illustrated, current flows C1 radiate generally from ribs 516toward tissue-contacting surface 518 along the edge radius 515 of sealplate 512. It is believed that the combination of edge radius 515 andribbed structure 516 promotes surface current flows C1 away from sidewall 520 of jaw member 500 and instead directs current flow along andacross edge radius 515 and tissue-contacting surface 518, which, inturn, reduces edge cutting of tissue around the perimeter of the sealplate 512. It is also believed that, by directing energy away from sidewall 520 in the manner just described, thermal spread may be reducedwithin tissue in the region the surrounding side wall 520, andsurrounding jaw member 500 generally.

In another aspect, it is believed that during use, currentconcentrations C2 form in a region generally surrounding ribs 516, andreduces or eliminates lateral propagation of electrosurgical energy fromside walls 520 of jaw member 500 into surrounding tissue. In turn, thedecreased sideward propagation of electrosurgical energy results incorresponding decrease of thermal spread to the untargeted, peripheralareas of tissue, while simultaneously concentrating electrosurgicalenergy to regions of tissue disposed between the tissue contactingsurface 518 of jaw member 500. In this manner, vessel sealing proceduresmay be performed with greater efficiency, with improved controllabilityand energy delivery and predictability of outcome, and ultimately leadto improved outcomes and decreased recovery times. Edge cutting may alsobe abated by the described mechanism of reducing lateral energypropagation, since the reduction of lateral energy impinging intosurrounding tissue contributes to the overall reduction of unwantedbuild-up of thermal energy in surrounding tissue.

While several embodiments of the disclosure have been shown in thedrawings, it is not intended that the disclosure be limited thereto, asit is intended that the disclosure be as broad in scope as the art willallow and that the specification be read likewise. Therefore, the abovedescription should not be construed as limiting, but merely asexemplifications of particular embodiments. Those skilled in the artwill envision other modifications within the scope and spirit of theclaims appended hereto.

1-20. (canceled)
 21. An end effector assembly for an electrosurgical instrument, comprising: a first jaw member and a second jaw member, at least one of the first jaw member or the second jaw member movable relative to the other to grasp tissue therebetween, at least one of the first jaw member or the second jaw member including: an electrode having a tissue contacting surface and a side wall extending from the tissue contacting surface, the side wall including a series of ribs and a series of spaces therebetween; and an insulator, wherein a portion of the insulator is disposed within each space of the series of spaces, wherein the series of ribs and the portions of the insulator are configured to define a current flow path from the side wall towards the tissue contacting surface such that electrosurgical energy is inhibited from propagating to untargeted tissue.
 22. The end effector assembly according to claim 21, wherein the tissue contacting surface includes a peripheral edge, the side wall extending from the peripheral edge of the tissue contacting surface.
 23. The end effector assembly according to claim 22, wherein a transition from the peripheral edge of the tissue contacting surface to the side wall defines an edge radius.
 24. The end effector assembly according to claim 23, wherein the edge radius is configured to direct the current flow path from the series of ribs towards the tissue contacting surface.
 25. The end effector assembly according to claim 21, wherein a current concentration is formed in a region surrounding the series of ribs, wherein the series of ribs is provided to inhibit the current concentration from propagating electrosurgical energy from the side wall to untargeted tissue.
 26. The end effector assembly according to claim 21, wherein the electrode defines an inverted U-shaped cross-section.
 27. The end effector assembly according to claim 21, wherein an outer surface of the insulator is flush with an outer surface of the side wall.
 28. The end effector assembly according to claim 21, wherein the tissue-contacting surface of the electrode defines a longitudinally-extending knife channel therethrough.
 29. The end effector assembly according to claim 21, wherein the electrode and the insulator are overmolded to one another.
 30. The end effector assembly according to claim 21, wherein a distance between adjacent ribs of the series of ribs is greater than a width of each rib of the series of ribs.
 31. The end effector assembly according to claim 21, wherein the at least one of the first jaw member or the second jaw member further comprises a jaw housing configured to support the electrode and the insulator.
 32. The end effector assembly according to claim 21, wherein the at least one of the first jaw member or the second jaw member further comprises a wire joined to the electrode and configured to supply electrosurgical energy thereto.
 33. An end effector assembly for an electrosurgical instrument, comprising: a first jaw member and a second jaw member, at least one of the first jaw member or the second jaw member movable relative to the other to grasp tissue therebetween, at least one of the first jaw member or the second jaw member including: an electrode having a tissue contacting surface and a side wall extending from the tissue contacting surface, the side wall configured to define a current flow path of electrosurgical energy from the side wall towards the tissue contacting surface; and an insulator disposed along at least a part of the side wall, the insulator configured to inhibit propagation of the current flow path of electrosurgical energy from the side wall to untargeted tissue.
 34. The end effector assembly according to claim 33, wherein the side wall includes a series of ribs and a series of spaces therebetween, and wherein a portion of the insulator is disposed within each space of the series of spaces.
 35. The end effector assembly according to claim 34, wherein the tissue contacting surface includes a peripheral edge, the side wall extending from the peripheral edge of the tissue contacting surface.
 36. The end effector assembly according to claim 35, wherein a transition from the peripheral edge of the tissue contacting surface to the side wall defines an edge radius.
 37. The end effector assembly according to claim 36, wherein the edge radius is configured to direct the current flow path from the series of ribs towards the tissue contacting surface. 